partridge-cpp/BENCHMARKING.md

Solver benchmarks

The benchmark suite records repeatable performance data independently of the default correctness tests. It exercises the exhaustive infeasible order 7 and the first-solution orders 8 and 9. The benchmark executable is opt-in:

cmake -S . -B build-benchmark -DCMAKE_BUILD_TYPE=Release \
  -DPARTRIDGE_BUILD_BENCHMARKS=ON
cmake --build build-benchmark
python3 benchmarks/run.py --binary build-benchmark/partridge_benchmark \
  > benchmark.json

The default policy is one unrecorded warm-up followed by five repetitions per case, with a 600-second timeout for each process. Solver stdout is captured; the probe renders into an in-memory stream so grids do not perturb terminal I/O. Override the policy with --orders, --warmup, --repetitions, and --timeout. Order 9 uses the constructive odd-order path, searching order 8 and then tiling the enlarged border, so it is suitable for normal local benchmarking:

python3 benchmarks/run.py --binary build-benchmark/partridge_benchmark \
  --orders 8 9 --warmup 1 --repetitions 5 --timeout 60 > benchmark.json

The JSON contains every run and median, range, and median absolute deviation for solve, construction, independent validation, and rendering. Direct-search cases report zero construction time: their setup and allocation remain part of solve time. Constructed odd-order cases report predecessor search and construction separately. The document also records compiler, flags, build type, commit, OS/CPU metadata, worker count, search policy, seed, timeouts, errors, invalid outputs, and the stdout policy. Search counts must be stable across repeated runs. Prune and task counters are zero for the current unpruned, single-threaded solver and reserve stable schema fields for later work.

The runner writes its JSON report before returning a failure status if any mode has no completed runs or produces an error or invalid output. Timeouts are reported but do not fail a case when another repetition completed.

Normal partridge_cpp calls instantiate a compile-time counter-free solver. Use --measure-overhead to run both counter-free and counted variants and report their median difference:

python3 benchmarks/run.py --binary build-benchmark/partridge_benchmark \
  --orders 8 --warmup 2 --repetitions 7 --timeout 60 --measure-overhead \
  > overhead.json

Counter-free and counted warm-ups and measurements are interleaved. The first mode alternates on each repetition, limiting systematic bias from temperature, frequency scaling, and run order. Reported overhead is the difference between the two independently summarized medians.

Do not use wall-clock thresholds as correctness checks. Keep the generated JSON outside version control unless it is being deliberately added as a named comparison baseline.

Post-correctness baseline

This framework starts from commit ce39d0a after the rendering assertion fix in #7 and completion check fix in #14. The earlier Apple M1 Release results in results.md are approximately 1.76 seconds for order 8 and 158.69 seconds elapsed for order 9; they predate the structured runner and do not contain search counters.

The first clean structured baseline used commit 598667b, Apple Clang 21.0.0 with -O3 -DNDEBUG, Apple arm64, one worker, one warm-up, and three measured repetitions. The runner reported a clean working tree:

Order	Result	Counted solve median (range)	Nodes	Placements	Backtracks
7	infeasible	3.453 s (3.444–3.455 s)	110,483,315	110,483,314	110,483,314
8	solution	1.817 s (1.814–1.817 s)	60,485,176	60,485,176	60,485,140

Counts were stable across repetitions. Interleaved counter-free medians were 3.435 seconds for order 7 and 1.805 seconds for order 8, giving counted overheads of 0.53% and 0.64% respectively. Construction time was zero; median independent validation and rendering times were each below 0.02 milliseconds.

Order 9 was not rerun for this initial baseline because the former direct search took several minutes. The default suite includes it with a per-run timeout.

Odd construction comparison

The order-9 construction was measured from the issue 6 working tree based on commit ddf07e7, using Apple Clang 21.0.0 with -O3 -DNDEBUG, macOS arm64, one worker, one warm-up, and three measured repetitions. Counter-free and counted runs were interleaved:

Order	Mode	Search median (range)	Construction median	Nodes
8	counter-free	1.773 s (1.770–1.775 s)	0	0
8	counted	1.849 s (1.848–1.850 s)	0	60,485,176
9	counter-free	1.778 s (1.773–1.779 s)	0.458 us	0
9	counted	1.852 s (1.845–1.912 s)	0.416 us	60,485,176

All runs completed with valid results and stable counters. The matching order-8 and order-9 search counts demonstrate that the new path searches only the predecessor. Compared with the recorded 158.69-second direct order-9 elapsed time in results.md, the 1.778-second counter-free median plus construction is approximately 89 times faster. The benchmark working tree was necessarily dirty with the issue 6 implementation.

New optimization issues should quote the exact JSON environment, policy, median/spread, stable counters, and counted overhead from this runner for both before and after revisions.